from Wiktionary, Creative Commons Attribution/Share-Alike License.
superlativeform of favourable: most favourable.
Sorry, no etymologies found.
Indeed, it does not seem possible that, in any of the favourablest outward circumstances, Johnson's life could have been other than a painful one.
But these commissions of my patrons came to an end; they could afford me no permanent establishment: and ever since, my wife has continued urging me still more to go upon the stage again; though, at present, alas, her own situation is none of the favourablest for exhibiting herself, with honour, in the eyes of the public.
But we will take the favourablest hypothesis ever started for the Parliament; the favourablest, though I believe it is not the true one, but too favourable.
Indeed, it does not seem possible that, in any the favourablest outward circumstances, Johnson's life could have been other than a painful one.